In photomasks (reticles) used for transferring a semiconductor device pattern, a transparent film called a pellicle is stuck to a pattern forming surface so as to protect the pattern. After exposure using a reticle is repeated, particles are stuck to the reticle. Therefore, it is necessary to wash the surface of the reticle using a drug solution in order to remove the particles. At this time, if the drug solution or moisture is stuck to the pellicle, the transmissivity of ultraviolet rays will vary, which makes it difficult to perform appropriate exposure. To avoid this, it is necessary to remove the pellicle when cleaning the reticle, and a new pellicle must be attached after the cleaning.
The process of peeling off the pellicle and that of reattaching a new pellicle may damage the pattern. In view of this, it is necessary to perform a pattern securing test. Thus, a long time is required until cleaning of the reticle is completed, and the reticle cannot be used for exposure during the long cleaning period. Further, the cost for pellicles is a factor of increasing the entire semiconductor manufacturing cost.
Furthermore, in EUV lithography, a vacuum chuck cannot be used as a chuck mechanism for an EUV mask, and an electrostatic chuck is employed instead. If a foreign particle is held between the surface of the chuck mechanism and the EUV mask, the mask will be deformed, thereby distorting the patterned surface.
Therefore, it is important to manage foreign particles by performing a foreign particle test for the chuck surface of the EUV mask, and when foreign particles are detected, it is eliminated by, for example, cleaning. However, if elimination by cleaning is performed, foreign particles may be reattached to the patterned surface. In this case, it is also necessary to perform, for example, a foreign particle test for the patterned surface, which requires a lot of time. As a result, the operating rate of the EUV exposure apparatus will lower.